Endogenous acetylcholine enhances synchronized interneuron activity in rat neocortex

Area of Science:

• Neuroscience
• Cellular Neuroscience
• Systems Neuroscience

Background:

• Interneurons play a crucial role in cortical network function.
• Nicotinic acetylcholine receptors (nAChRs) are known to excite neocortical interneurons.
• Acetylcholine (ACh) may influence the synchronization of local neocortical interneuronal networks.

Purpose of the Study:

• To investigate the influence of acetylcholine (ACh) on synchronized activity in local neocortical interneuronal networks.
• To determine the specific nAChR subtypes involved in ACh-mediated modulation of cortical network activity.

Main Methods:

• Utilized voltage-sensitive dye imaging with RH 414 in rat neocortical slices.
• Applied 4-aminopyridine (4-AP) and excitatory amino acid (EAA) receptor antagonists to induce synchronized activity.
• Administered ACh esterase inhibitors and nAChR agonists/antagonists to assess their effects on network activity.

Main Results:

• Bath application of neostigmine and the nAChR agonist DMPP increased the amplitude, spread, and duration of synchronized activity in upper cortical layers.
• The muscarinic AChR antagonist atropine did not block the enhancement of activity by neostigmine.
• The selective alpha4beta2-like nAChR antagonist dihydro-beta-erythroidine blocked the effect of neostigmine, while the alpha7-like nAChR antagonist methyllycaconitine was ineffective.

Conclusions:

• Activation of alpha4beta2-like nAChRs enhances synchronized activity in local neocortical inhibitory networks.
• Endogenously released ACh likely modulates cortical network synchronization through alpha4beta2 nAChRs.
• These findings suggest a novel mechanism for regulating brain network dynamics.